Misfire, Intermittent, 89 S10 Blazer
 

I have an 89 S10 with 4.3 "Z" engine. It misfires at random times and craps out at times. Once cool again, it behaves for a while. The rotor, dist cap, coil and coil wire were done 7,200 miles ago. The plugs and wires about 17,000. I have a new sender and gas tank. It runs great when not having this problem. My mech wants to start with new plugs & wires as well as the dist cap, coil, etc. DOES ANYONE KNOW OF ANY OTHER THINGS TO CHECK ON THIS TYPE OF VEHICLE AS WELL? Thank you very much.

Have you checked out the Fuel Filter?

What is the humidity like during this? If it is more humid out when it is misfiring, then I would agree, a general tune up (plugs, wires, cap, & rotor) would eliminate the ignition system. You can test the coil and I would definitely recommend doing so before just replacing it.

Solved
 

It looks like the EGR failed. There was also a build up of water in the distributor. The spark plug gap was @ 100 vs. the 60 spec. He replaced the dist cap, dist rotor and the plugs. Runs fine again. Thank you.

The fuel filter was replaced when I did the gas tank. A pin hole in the lines back there had to be done so I did a new tank. There was a lot of rust back there. Thanks